I have an Aspire One, and while I am growing fond of Aros, I can not deny that MorphOS is light years ahead. And I've also heard that it is snappier than OS 4, but can not confirm this.
Also for the note, there are a slew of classic Amiga apps that run just fine on MorphOS without being bothered by the lameness that is UAE.
Not trying to start a flame war of course, I just want MorphOS' many strengths to be known so more people might give it a look. It's awesome!